Waterfall Garden Park, Privately owned public garden in Pioneer Square, Seattle, United States.

Waterfall Garden Park is a 60-by-80-foot pocket park in Pioneer Square, created in 1978 on the site of the original United Parcel Service building. Its centerpiece is a manmade 22-foot waterfall pumping 5,000 US gallons of water per minute, set among Japanese garden plantings and a pool designed by Yoshikuni Araki.

The garden was established in 1978 as a memorial to James Casey, founder of United Parcel Service, on the original site of the UPS headquarters building. Its creation was part of an urban renewal effort in the Pioneer Square neighborhood.

The garden's name comes from the 22-foot waterfall, which pumps 5,000 US gallons of water per minute. Its Japanese garden includes Chamaecyparis obtusa and other botanicals native to Japan, plus a pool designed by Yoshikuni Araki. The planting won the Environmental Award of the American Nurserymens Association in 1981.

The park is open to the public during the day and locked at night. It occupies a 60-by-80-foot (18 by 24 m) lot in Pioneer Square, entered from the street; seating is provided around the pool and waterfall.

When created, this garden ranked among the most costly parks per square foot ever built in the nation. Such an investment in a small urban space remains uncommon for most American cities.